1. Field of Invention
The present invention relates generally to tools, and more particularly to tools adapted to assist in the installation and removal of U-nut fastener clips.
2. Description of the Prior Art
U-nut fastener clips enable the use of threaded fasteners for connecting an object to sheet metal or other sheet material. A U-nut clip is typically made from spring steel or other resilient metal, and is formed with a base portion and a pair of spaced legs extending therefrom to define a generally U-shaped body. A tongue, resiliently connected to one of the legs, is formed with a bend or elbow portion which extends toward the second leg, and a centrally located clearance hole. A threaded barrel aligned with the clearance hole in the tongue extends from the second leg for receiving a threaded fastener. U-nuts of this general type are shown in, for example, Peterson et al., U.S. Pat. No. 4,729,706, and Peterson et al., U.S. Pat. No. 4,897,005.
As discussed in the Peterson patents, U-nut fastener clips are typically designed for ease of installation, for pressing the clip onto the sheet metal with the legs straddling the edge of the sheet metal. As the clip is pushed into position, the tongue flexes away from the second leg, slides along the face of the edge, and then snaps back as the elbow aligns with and snaps into a clearance hole formed in the sheet metal to retain the clip in position.
As a consequence of the desire for ease of installation and the resulting construction of U-nut fastener clips, removal of such clips may be difficult as the elbow must be drawn and maintained from engagement with the clearance hole as the clip is slipped on the edge of the sheet metal. Typically, the blade of a screwdriver, or the tip of a relatively narrow or pointed tool, is inserted between the sheet metal and a portion of the tongue such as the free end of the tongue to pry the tongue away from the sheet metal. The U-nut is then pushed or pulled off the sheet metal, while continuing to pry the tongue from the sheet metal to prevent the tongue from snapping back into the clearance hole. In certain instances, a clip may be removable by pressing on the pry tool in the direction toward the edge of the sheet metal while simultaneously prying the tongue from the clearance hole in the sheet metal. However, this method presents a danger that the clip will "spring" from the sheet metal as it is pressed off the edge, or that the clip will fall into an unreachable or generally undesirable location. Therefore, safe, controlled removal of U-nut fastener clips with such tools typically requires the use of two hands, one to pry the tongue from the sheet metal, and the other to simultaneously pull the clip from the edge of the sheet metal. Thus, removal of U-nut fastener clips can be particularly difficult where the clip is located in cramped quarters, or in difficult-to-reach places, because of the need to typically use two hands.
The inventor is aware of no tool that is especially adapted for removal of U-nut fastener clips. The only prior tool adapted for use with any type of fastener clip that the inventor is aware of is a pliers-like hand tool sold under the name PODNEY pliers by Steck Manufacturing Co. of Dayton, Ohio for removing J-nut fastener clips. J-nut clips are formed with a base and a pair of spaced legs extending therefrom, with one leg being typically formed at about one-half the length of the other leg to define a generally J-shaped body. The threaded barrel extends from the longer leg, and the shorter leg is formed with a free end raised or extending toward the longer leg to restrict the clearance between the legs and to be received into the clearance opening in the sheet metal to retain the clip in position.
The PODENY pliers includes one jaw formed with a U-shaped notch for receiving the base of a J-nut fastener clip, and an opposing jaw formed with a tip aligned with the notch in the other jaw. To remove a J-nut clip with the PODNEY pliers, the tip is positioned between the free end of the shorter leg and the sheet metal, and the notch is aligned with base of the clip. The handles are then squeezed together to clamp the clip between the jaws, and rotated about the base of the clip to twist the free end of the shorter leg from the clearance hole in the sheet metal for removal of the clip.
However, the PODENY pliers is not particularly useful in connection with removing U-nut fastener clips because use of the tool would require the user to bend the leg to which the tongue is connected to release the clip from the sheet metal. A primary deficiency with this approach is that, the tongue, not the base, of a U-nut clip is designed to flex during installation and removal, and the base of the U-nut clip is typically relatively stiff to help maintain the clip in place on the sheet metal. Thus, substantial twisting torque would need to be applied to the handles of the PODENY tool to release the tongue from the sheet metal. Use of the PODENY pliers can also result in substantial friction that must be overcome during removal of the clip because the leg to which the barrel is attached reacts the twisting force of the tool against the sheet metal. In addition, the PODENY pliers tends to be a relatively long tool to assist in developing the relatively high torque needed to bend fastener clips about the relatively stiff base for removal of such clips. For these reason, use of the PODENY pliers can be awkward and difficult in connection with U-nut clips, in many instances is no easier than conventional two-handed removal of a U-nut clip with a pointed tool, and is generally of no assistance in cramped locations or locations for which clear access is not available to the tongue side of the clip.
Thus, there is a need for a tool adapted to assist with removal of U-nut fastener clips, and particularly for a hand tool adapted to assist with safe and easy one-handed removal of such clips, even though the clips may be located in difficult to reach places.